Nuntio AI API keys provide prepaid credit through an OpenAI-compatible interface. A key is funded from a Nuntio account in AUSD, and its purchase and top-ups are subject to the account’s spending policies. Compatible clients send requests to Nuntio’s gateway using the key and a base URL. The gateway supports listed chat, image-generation, and audio-transcription endpoints; the available models are returned by its models endpoint. Requests are limited by the key’s remaining balance, and the documentation describes balance and verification information in response headers.